1. The Field of the Invention
This invention relates to an electroconvergent cautery system employing forceps or probes which produce sharply localized heating for cutting, vaporizing tissue and coagulating blood vessels when brought into contact with the same. More particularly, it concerns a method for using an electroconvergent cautery system.
2. The Background Art
Electrocautery systems are known in the art for coagulating vessels and for cutting tissue. Two common types of electrocautery systems are the monopolar and the bipolar systems. In the monopolar systems, high frequency electric current is passed from the cautery probe through the tissue to the grounding pad. Heat is generated in the tissue at the site of contact of the probe tip to the tissue. This heat is generated, by the flow current through the electrical resistance of the tissue in the preferred path between the probe tip contact site and the grounding pad. In such devices, the current is continuous sinusoidal or amplitude modulated. The monopolar system fails to provide uniform heating because tissue does not have uniform resistance and the tissue of lower resistance is the preferred path of current. For this reason, as the current flows from the point of contact of the probe to the surrounding tissue, heating tends to spread beyond the contact point of the probe to the surrounding tissue. This causes undesirable damage to the surrounding tissue. These problems of tissue damage were overcome by the bipolar system.
The bipolar system typically uses forceps to provide two tips. One tip is similar to the monopolar device and allows current to be supplied to the tissue while the other tip provides a return path for the current. By using two tips, the spread of current is limited to the path between the two tips and the current is prevented from spreading to the surrounding tissues and causing undesirable tissue damage. The monopolar and bipolar systems are able to cut tissue and coagulate vessels, but they cannot effectively vaporize tissue.
A lesion generator known as a radio frequency (RF) lesion generator is known in the art and works on the same principles as the monopolar cautery system except that a lower level of current is used and the current is of the continuous sinusoidal type. This current type results in more uniform tissue destruction. However, such a system is used exclusively for creating lesions.
In an effort to resolve the problems of the prior art, the inventors invented a method for using a radio frequency surgical tool which is disclosed in U.S. Pat. No. 5,019,076. This tool is capable of cutting and vaporizing tissue and coagulating vessels without the spread of heat to the surrounding tissue. In the device of said patent, a high frequency (13.56 or 27.0 MHz) current is passed through an amplifier, a matching network and a solenoid coil to generate an electromagnetic field. This in turn induces eddy currents in the tissue. Touching the tissue with a probe which is AC-coupled to a return circuit draws the eddy currents out of the tissue at the contact point of the probe producing intense heat which can cut and vaporize tissue as well as coagulate vessels. One disadvantage of the system of the said patent is that the proximity of the coil to the operative field causes inconvenience to the surgeon. A further disadvantage of the device of said patent is that the coagulating ability of the device is not as efficient as desired. Another disadvantage of the device is that it requires a grounding component.
Of current interest is a method for surgical treatment wherein a probe is used with an RF lesion generator to surgically treat tissue in a patient. This method overcomes the disadvantages of the prior art because the method provides means for surgical treatment using an RF generator without the necessity of a solenoid coil or a grounding component.